Signal recording method &amp; apparatus, signal recording / reproducing method &amp; apparatus and signal recording medium

ABSTRACT

By reducing the number of seek operations in an operation to play back a signal from a recording medium, the amount of data temporarily stored in a read buffer memory employed in a signal recording/playback apparatus is large enough to be output as a playback signal during a seek operation, allowing a continuous playback operation to be carried out. In order to reduce the number of seek operations, a signal is always recorded onto the recording medium in continuous free areas each having a size equal to or larger than a predetermined recording/playback time length which is typically set at 1 minute. If it is necessary to insert an additional signal having a length smaller than the predetermined recording/playback time length into a point of insertion in an area already occupied by an existing signal, a continuous free area with a size equal to or larger than the predetermined recording/playback time length is newly allocated to the additional signal. The additional signal is then recorded in the free area instead of being inserted into the point of insertion. Since the free area is larger in size than the length of the additional signal, the rest of the free area is filled up with a portion of the existing signal adjacent to the point of insertion.

BACKGROUND OF THE INVENTION

The present invention relates to a technology for recording and playingback signals such as video and audio signals into and from an erasablerecording medium such as an optical magnetic disc, a variable phase discand a magnetic disc.

By virtue of development of band compression technologies represented bythe recently introduced MPEG (Moving Picture Experts Group)compression/coding technology, signals such as audio and video signalscan now be recorded into a large capacity recording medium such as anoptical magnetic disc for a playback operation of a long time.

When a signal is recorded into such a recording medium, the signalundergoes a band compression/coding process, being recorded in sectorunits. The signal is then recorded into free areas on the recordingmedium.

Traditionally, a signal continuous in the time axis direction resultingfrom typically editing work such as an audio or video signal is recordedinto a recording medium, being split into segments as shown in FIG. 21(1). In the figure, the symbol # on each of the segments indicates theorder number in an operation to play back the signal. While the segmentsof the signal are arranged along a straight line as shown in the figure,the signal is actually recorded on a track having a spiral shape orconcentric tracks on the recording medium.

Consider a playback operation in which segment #5 is reproduced aftersegment #4. In this case, a reproduced signal generated by a read pickupis broken due to a seek time, a rotation wait time and a settle timewhich are required between segments #4 and #5. The seek time is a periodof time it takes to move the read pickup in a so-called track jump to atrack in area where segment #5 is recorded. On the other hand, therotation wait time is a period of time it takes to wait for the readpickup to arrive at the position of a target sector on the track.Finally, the settle time is a period of time it takes the tracking servoof the read pickup to get settled.

In order to prevent a playback signal eventually generated by therecording/playback apparatus from being broken even if the reproducedsignal generated by the read pickup is unavoidably broken as describedabove, a read buffer memory is provided for storing in advance a signalread out from the recording medium. The signal stored in the read buffermemory is used for filling up the time gap between two consecutivesegments, that is a period of time during which no reproduced signal isgenerated by the read pickup. The signal stored in the read buffermemory is then output when the reproduced signal generated by the readpickup is broken.

In the case of a recorded signal split into a large number of segmentsas shown in FIG. 21 (2), however, it is quite within the bounds ofpossibility that the amount of data stored in advance in the read buffermemory during the time is not large enough to be used for filling up atime gap between two consecutive segments. As a result, the eventualplayback signal can not be generated continuously.

SUMMARY OF THE INVENTION

The present invention addresses the problems described above. It is thusan object of the present invention to provide a technology that makes acontinuous playback operation possible by assuring that the amount ofdata stored in a read buffer memory is large enough for eliminating aplayback time break through reduction of the number of seek operations.

In order to achieve the object of the present invention, the presentinvention provides a signal recording method whereby, in an operation torecord a signal onto a recording medium, the signal is recorded incontinuous free areas each having a size equal to or larger than apredetermined recording/playback time length.

In addition, the present invention also provides a signalrecording/playback method wherein, in an operation, to insert anadditional signal having a length smaller than a predeterminedrecording/playback time length into a point of insertion in an area on arecording medium already occupied by an existing signal the signalrecording/playback method is implemented by executing the steps of:

-   -   newly allocating a continuous free area on the recording medium        with a size of at least the equivalence of the predetermined        recording/playback time length to the additional signal;    -   recording the additional signal in the continuous free area; and    -   filling up the rest of the continuous free area with a portion        of the existing signal adjacent to the point of insertion.

Furthermore, the present invention also provides a signalrecording/playback method wherein, in case a signal already recorded ona recording medium has a continuous segment smaller in size than anequivalence of a predetermined recording/playback time length, thesignal recording/playback method is implemented by executing the stepsof:

-   -   newly allocating a continuous free area on the recording medium        with a size of at least the equivalence of the predetermined        recording/playback time length to the segment;    -   relocating the segment to the continuous free area; and    -   filling up the rest of the continuous free area with a portion        of the signal adjacent to the segment.

On the top of that, the present invention also provides a signalrecording apparatus for recording a signal onto a recording medium, theapparatus comprising:

-   -   a 1st means for recognizing a continuous free area on the        recording medium with a size equal to or larger than a        predetermined recording/playback time length; and    -   a 2nd means for executing control to record a signal onto the        continuous free area.

In addition, the present invention also provides a signal recording/playback apparatus for recording and playing back a signal onto and from arecording medium, the apparatus comprising:

-   -   a 1st means for recognizing a continuous free area on the        recording medium with a size equal to or larger than a        predetermined recording/playback time length; and    -   a 3rd means for executing control to record a signal, which is        supposed to be newly inserted into a point of insertion in an        area on the recording medium already occupied by an existing        signal, onto the continuous free area and to fill up the rest of        the continuous free area with a portion of the existing signal        adjacent to the point of insertion.

Furthermore, the present invention also provides a signal recording/playback apparatus for recording and playing back a signal onto and from arecording medium, the apparatus comprising:

-   -   a 1st means for recognizing a continuous free area on the        recording medium with a size equal to or larger than a        predetermined recording/playback time length; and    -   a 4th means for executing control to relocate a continuous        segment of a signal already recorded on the recording medium        having a size smaller than a predetermined recording/playback        time length and to fill up the rest of the continuous free area        with a portion of the already recorded signal adjacent to the        segment.

On the top of that, the present invention also provides a signalrecording medium wherein a signal is recorded into continuous areas eachhaving a size equal to or larger than a predetermined recording/playbacktime length.

According to one aspect of the present invention, there is provided asignal recording apparatus provided for recording a signal onto arecording medium wherein:

-   -   a 1st means is used for recognizing a continuous free area on        the recording medium with a size equal to or larger than a        predetermined recording/playback time length; and    -   a 2nd means is used for executing control to record a signal        onto the continuous free area.

In addition, according to another aspect of the present invention, thereis provided a signal recording/play back apparatus for recording andplaying back a signal onto and from a recording medium wherein:

-   -   a 1st means is used for recognizing a continuous free area on        the recording medium with a size equal to or larger than a        predetermined recording/playback time length; and    -   a 3rd means is used for executing control to record a signal,        which is supposed to be newly inserted into a point of insertion        in an area on the recording medium already occupied by an        existing signal, onto the continuous free area and to fill up        the rest of the continuous free area with a portion of the        existing signal adjacent to the point of insertion.

On the top of that, according to a further aspect of the presentinvention, there is provided a signal recording/play back apparatus forrecording and playing back a signal onto and from a recording mediumwherein:

-   -   a 1st means is used for recognizing a continuous free area on        the recording medium with a size equal to or larger than a        predetermined recording/playback time length; and    -   a 4th means is used for executing control to relocate a        continuous segment of a signal already recorded on the recording        medium having a size smaller than a predetermined        recording/playback time length and to fill up the rest of the        continuous free area with a portion of the already recorded        signal adjacent to the segment.

BRIEF DESCRIPTION OF THE DRAWINGS

An embodiment of the present invention will be described by reference tothe following diagrams wherein:

FIG. 1 is a block diagram showing the configuration of a signalrecording/playback apparatus to which the present invention is applied;

FIGS. 2 (1) and (2) are diagrams each showing a layout of a signal on adisc undergoing an operation to record an additional signal portioncarried out by the signal recording/playback apparatus onto the disc;

FIG. 3 is a diagram showing locations of 3 programs recorded in 3 fileson the disc with locations of each of the files represented by astraight line pattern;

FIG. 4 is a table showing an example of file system control informationcomprising entries to be referenced by a file system;

FIG. 5 shows an example of a FAT (File Allocation Table);

FIG. 6 is a diagram showing a technique for implementing control of afixed rate to be achieved in a 1-minute period of time;

FIG. 7 is a block diagram showing the configuration of an apparatusimplementing the fixed rate control;

FIG. 8 shows a flowchart representing an encoding process forimplementing the fixed rate control;

FIGS. 9 (1) to 9 (5) are diagrams showing layouts of a signal recordedon the disc of the signal recording/playback apparatus shown in FIG. 1in an editing process;

FIGS. 10 (1) and 10 (2) are diagrams showing general optimization of asignal;

FIGS. 11 (11) to 11 (5) are diagrams showing general optimization of asignal carried out in the embodiment;

FIG. 12 is a diagram showing a signal to be edited in the embodiment;

FIGS. 13 (1) to 13 (5) are diagrams showing examples of editing workcarried out on a signal;

FIGS. 14 (1) to 14 (5) are diagrams showing other examples of editingwork carried out on a signal;

FIGS. 15 (1) to 15 (4) are diagrams showing still other examples ofediting work carried out on a signal;

FIGS. 16 (1) to 16 (4) are diagrams showing further examples of editingwork carried out on a signal;

FIGS. 17 (1) to 17 (5) are diagrams showing still further examples ofediting work carried out on a signal;

FIGS. 18 (1) to 18 (3) are diagrams showing still further examples ofediting work carried out on a signal;

FIGS. 19 (1) to 19 (4) are diagrams showing still further examples ofediting work carried out on a signal;

FIGS. 20 (1) to 20 (3) are diagrams showing still further examples ofediting work carried out on a signal; and

FIGS. 21 (1) and (2) are explanatory diagrams used for describing theordinary method to play back a signal.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

The above and other objects, features as well as many of the attendantadvantages of the present invention will become more apparent and, thus,more readily appreciated as the game becomes better understood from acareful study of the following detailed description of a preferredembodiment of present invention with reference to the accompanyingdiagrams. The description is divided into sections listed below whichare explained sequentially in the order the sections are put on thefollowing list:

-   1 Configuration of the Signal Recording/Playback. Apparatus,-   2 Recording of an Additional Signal-   3 Recognition of Free Areas-   4 Editing-   5 optimization-   6 Editing Details.    1 Configuration of the Signal Recording/Playback Apparatus

FIG. 1 is a block diagram showing the configuration of a signalrecording/playback apparatus to which the present invention is applied.The signal recording/playback apparatus records and plays back video andaudio signals into and from a solid memory represented by an opticalmagnetic disc, a magnetic disc, a magnetic tape and a semiconductormemory in addition to a data recording medium in general by multiplexingthe signals. In order to simplify the description, however, only anoptical magnetic disc which is referred to hereafter simply as a disc isexplained as a representative.

In this signal recording/playback apparatus, a system controller 1controls the apparatus as a whole in addition to carrying out otherfunctions. A video encoder 2 performs a video encoding process on avideo signal supplied thereto. By the same token, an audio encoder 3carries out an audio encoding process on an audio signal suppliedthereto. A multiplexer 4 multiplexes the outputs of the video and audioencoders 2 and 3. A write buffer memory 5 is used for temporarilystoring the output of the multiplexer 4. A pickup 6 is used for writingthe output of the write buffer memory 5 onto a disc. In addition; thepickup 6 is also used for reading out a playback signal from the discand outputting the signal played back from the disc to a read buffermemory 7 which is used for temporarily storing the signal read out fromthe disc by the pickup 6. A demultiplexer 8 splits the output of theread buffer memory 7 back into video and audio data. A video decoder 9carries out a video decoding process on the video data resulting fromthe split done by the demultiplexer 8. By the same token, an audiodecoder 10 carries out an audio decoding process on the audio dataresulting from the split done by the demultiplexer 8.

2 Recording of an Additional Signal

FIGS. 2 (1) and (2) are diagrams each showing recording a layout of asignal on a disc undergoing an operation to record an additional signalportion by the signal recording/playback apparatus onto the disc. To bem more specific, FIG. 2 (1) is a diagram showing a recording layoutprior to the additional recording operation and FIG. 2 (2) is a diagramshowing a recording layout after the additional recording operation. Inthe figures, a portion shown as a thin mesh denotes an area in which thesignal is recorded. As shown in the figure, an additional signal is notsplit into segments to be each recorded into a freed area with a lengthsmaller than a predetermined value, typically an equivalent of the1-minute recording/playback time length. Instead, the additional signalis recorded into a continuous free area with a length equal to or largerthan the 1-minute recording/playback time length.

3 Determination of Free Areas

This section explains a means for recognizing a continuous free area ofat least the predetermined typical value, that is, an equivalent of the1-minute recording/playback time length in length.

(a) Means for Recognizing Free Areas

Information on files on the disc is all recorded in a TOC (Table ofContents) area. At the time the disc is mounted on the signalrecording/playback apparatus, the system controller 1 reads out thisinformation on files from the TOC area and controls the files on thedisc till the disc is taken out from the apparatus. In order to controlfiles on the disc, the system controller 1 is provided with a FAT (FileAllocation Table) 11. The location and attributes such as the number,the recording date & time and the file name of each file on the disc arecontrolled by referencing the FAT 11. The FAT 11 is used for controllingthe information on files in smallest access units, typically sectorunits, used by the system, that is, the signal recording/playbackapparatus for making an access to the disc. It should be noted that, inthis embodiment, 1 sector is 2,048 bytes (or 2 K bytes) in size.

FIG. 3 is a diagram showing locations of 3 programs recorded in 3 fileson the disc with locations of each of the files represented by astraight line pattern. For example, continuous data of Program 1 isrecorded by splitting the data into 3 segments forming a pattern along astraight line for physical reasons encountered during an operation torecord the data onto the disc.

As shown in the figure, a file system in the system controller 1controls information on the file of Program 1 by keeping recordsindicating that the data of Program 1 is recorded continuously fromsectors 1 to 7 and then jumps to sector c in the FAT 11. The file systemobtains information on free areas by scanning the FAT 11. It should benoted that this technique of controlling information on files can be thesame technique as that adopted by a file control system of an ordinarycomputer.

File system control information including the FAT 11 described above isall written into the TOC area before the disc is taken out from thesignal recording/playback apparatus.

FIG. 4 is a table showing an example of file system control information.Provided for a file, each entry of the table includes attributeinformation of the file such as the name of the file (that is, the nameof a program stored in the file), a recording date & time, a recordingchannel, a recording time and a first sector of the file as shown in thefigure. When an access is made to a file, the file system refers to theentry for the file and starts the access. It is needless to say thatother file attribute information can be added to the table.

FIG. 5 shows an example of the FAT 11. The example is a table for dataof a program which is not recorded in physically consecutive sectors onthe disc. In this case, for each sector storing the data, the number ofa next sector for storing the same data is recorded. In order to makethe table shown in the figure easy to understand, a free area isrepresented by blanks. In actuality, however, the free area is filled upwith codes “000”. The end of a file is indicated by a code “fff”. Thus,a free area is found by sequentially scanning the left column of the FATstarting from sector 000 and ending at a sector with the next sectorthereof on the right column having a blank (“000”) sector number. Thesize of a free area is found by counting the numbers of physicallyconsecutive sectors included in the free area.

(b) Searching for a Free Area with a Size Greater than an Equivalent ofthe 1-Minute Recording/Playback Time Length

There are 4 methods which can be adopted by the file system for forminga judgment as to whether or not the size of a physically continuous freearea is at least an equivalent of the 1-minute recording/playback timelength.

According to a 1st method, the judgment is formed by determining whetheror not the free area can be used for accommodating data recorded for aperiod of time of at least 1 minute at the maximum recording rate.According to a 2nd method, the amount of data recorded for a 1-minuteperiod of time is first calculated by assuming a fixed recording rate ineach measurement time unit. The recording rate may vary from unit tounit. It should be noted, however that, since the measurement time unititself is also typically 1 minute in length anyway, in actuality, therecording rate can be assumed to be fixed during the 1-minute period oftime. The judgment is then formed by comparing the calculated amount ofdata with the size of the free area. According to a 3rd method, thejudgment is formed by simply determining whether or not the size of thefree area is greater than a predetermined amount of data typicallyexpressed in terms of bytes instead of the amount of data recorded for a1-minute measurement time used in the 2nd method. According to a 4thmethod, the amount of data recorded for a 1-minute period of time isfirst calculated by assuming a fixed recording rate during the 1-minuteperiod of time. In this case, the amount of data resulting from thecalculation is also fixed. The judgment is then formed by comparing thecalculated amount of data with the size of the free area. The 2ndmethod, a representative one among the 4 methods, is explained asfollows.

In order to implement a fixed recording rate (that is, a fixed encodingbit rate) during the 1-minute period of time prescribed by the 2ndmethod, it is necessary to execute control so that the number of bitsgenerated by the video encoder which is typically implemented by anMPEG2 encoder in 1 minute is constant.

A degree of difficulty of carrying out video encoding on a picture isdefined as a product of the number of generated bits and an averagequantization width in 1 picture. In the so-called variable rate encodingprocess, the number of generated bits is adjusted as follows. In thecase of a picture requiring video encoding at a high degree ofdifficulty, encoding needs to be carried out at an encoding bit rategreater than the past average bit rate to allocate a number of generatedbits larger than what would be obtained at the average bit rate in thepast to a complex picture. In the case of a picture requiring videoencoding with a low degree of difficulty, on the other hand, encodingcan be performed at an encoding bit rate smaller than the past averagebit rate to allocate a number of generated bits smaller than what wouldbe obtained at the average bit rate in the past to a simple picture.

In order to make the rate of generated bits fixed within the 1-minuteperiod of time, on the other hand the actual rate of generated bits isfed back to be compared with a target value. To put it in detail, if thetotal amount of code generated in the past is found smaller than aproduct of a target average bit rate and the lapse time, the number ofallocated bits is increased. If the total amount of code generated inthe past is found greater than the product of the target average bitrate and the lapse time, the number of allocated bits is decreased. As aresult, when viewed over along a period of time of typically 1 minute,recording is still carried out at a fixed bit rate by virtue of aneffect provided by the feedback system. At the same time, a large numberof bits and a small number of bits are still allocated to complex andsimple pictures respectively as a result of the application of thevariable rate encoding process described above, giving rise to an effectthat, a characteristic of a variable encoding bit rate for differentkinds of picture that enables transmission without sacrificing thequality of the picture is sustained as it is.

With the variable rate encoding process and the feedback system appliedas they are, however, there is no assurance that a target average bitrate can be achieved with a very high degree of accuracy. In order tosolve this problem, an adapted feedback loop with a feedback gain Gshown in FIG. 7 is used. In this feedback loop, the gain G is raisedapproximately before a time of typically 50 seconds lapses since thestart of the 1-minute period of time, so that the actual total amount ofgenerated code is forcibly brought to a value equal to the product of atarget average bit rate and the lapse time. To put it concretely, thedifference between the actual total amount and the product at a point oftime a 50-second period of time has lapsed since the start of the1-minute period of time is brought to a value within a range ALPHA asshown in FIG. 6 by raising the gain G sometime prior to the point oftime.

FIG. 8 shows a flowchart representing an encoding process. As shown inthe figure, the flowchart begins with a step S1 at which a targetaverage encoding bit rate, a maximum encoding bit rate, a minimumencoding bit rate and other parameters such as the range ALPHA are set.

The flow of the encoding process then goes on to a step S2 to form ajudgment as to whether or not a signal being input is the head of a GOP(Group of Pictures). If the head of a GOP is input, the flow of theencoding process proceeds to a step S3 at which the amount of generatedcode for an I picture is computed. Then, the flow of the encodingprocess continues to a step S4 at which the number of allocated bits iscomputed and the quantization width is adjusted to a value between themaximum and minimum encoding bit rates. In addition, a quantizationtable is created. Subsequently, the flow of the encoding process goes onto a step S5 at which all macroblocks of a picture are encoded. The flowthen proceeds to a step S6 at which the number of generated bits iscounted. The number of generated bits is used in the adjustment of thequantization width carried out at the step S4. If the outcome of thejudgment formed at the step S2 indicates that the input signal is notthe head of a GOP, on the other hand, the flow of the encoding processcontinues directly to the step S5.

In the encoding process described above, the quantization width isdetermined so that the actual amount of generated code can be brought toa value all but equal to the target code value at the last GOP. Itshould be noted that the number of allocated bits can also be controlledin picture units in place of GOP units. In addition, changing thequantization width is equivalent to manipulating a quantization table (aQ table) in the case of the MPEG encoding.

4 Editing

FIGS. 9 (1) to 9 (5) are diagrams showing layouts of a signal recordedon the disc of the signal recording/playback apparatus shown in FIG. 1in a typical editing process.

In this typical editing process, assume that portion #2 with a length ofsmaller than the 1-minute recording/playback time length is moved fromits original position in a signal shown in FIG. 9 (1) to a point ofinsertion indicated by an arrow by insertion. As the process to rewritethe signal due to the insertion of portion #2 is completed, the newlayout of the signal is changed to that shown in FIG. 9 (2). In theinsertion, the process to rewrite portion #1 of the signal behind thepoint of insertion takes a lot of time and labor.

In order to solve the problem described above, the signal is edited froma layout shown in FIG. 9 (3) to a layout shown in FIG. 9 (4). To put itin detail, a continuous free area with a length equal to or larger thanthe 1-minute recording/playback time length on the disc is allocated. Inthe free area, portion #2 and a part in portion #1 in front of the pointof insertion shown in FIG. 9 (1) on the time axis are written into thefree area to fill up the free area, resulting in the layout shown inFIG. 9 (4). Assume that the free area is an equivalent of the 1-minuterecording/playback time length in length as shown in the layout of FIG.9 (3). In this case, the length of the part of portion #1 moved to thefree area that is, the length of area A shown in FIG. 9 (4), is equal to(the length corresponding to a recording time of 1 minute—the length ofportion #2). As a result of the work to edit the signal from the layoutshown in FIG. 9 (3) to that shown in FIG. 9 (4), the resultingcontinuous blocks each have a length greater than an equivalent of the1-minute recording/playback time length. Thus, seek operations arecarried out at intervals longer than 1 minute, providing a period oftime between two consecutive seek operations which is long enough forfilling the read buffer memory with data of an amount sufficiently largeto be output during a track jump. As a result, a playback operation canbe carried out without a playback time break. It should be noted that#1, #2, #3 and #4 in the layout shown in FIG. 9 (5) are consecutivenumbers in the time axis direction which correspond respectively to #1at the left end, #1 and #2 at the right end, #1 in the middle and #3 inthe layout shown in FIG. 9 (4).

In the work to edit the signal from the layout shown in FIG. 9 (3) tothat shown in FIG. 9 (4) described above, area A, the data of which ismoved to the free area, is located in front of the point of insertion.It should be noted that, however, area A can be located behind the pointof insertion. In this case, the data of area A is moved to a location inthe free area behind portion #2. As an alternative, area A can comprise2 sub-areas sandwiching the point of insertion. In this case, portion #2in the free area is sandwiched by 2 pieces of data moved from the 2sub-areas of area A respectively.

5 Optimization

Consider a case in which segments #1 to #16 of a signal recorded on thedisc are consecutive in the time axis direction but not recorded atphysically continuous areas as shown in FIG. 10 (1). The segments can berearranged in a so-called defragmentazion process so that they arerecorded at physically continuous areas as shown in FIG. 10 (2). In thiscase, however, it takes a very long time to rearrange the segments assuch and the rearrangement can not be the to be always practical.

In order to solve the problem described above, in this embodiment, onlysegments each with a length of smaller than the 1-minuterecording/playback time length recorded in scattered areas are treatedas a target of rearrangement in order to make all continuous blocks ofthe signal at least the equivalent of the 1-minute recording/playbacktime length in size. Consider, for example, a signal with only segment#3 having a length of smaller than the 1-minute recording/playback timelength as shown in FIG. 11 (1). In this case, first of all, a free areawith a size of an equivalent of the 1-minute recording/playback timelength is allocated and segment #3 is moved thereto to result in alayout shown in FIG. 11 (2). Then, a portion at the head of segment #4with a length equal to (a length corresponding to the equivalent of the1-minute recording/playback time length—the length of segment #3) is cutout and moved to the free area behind segment #3 as shown in FIG. 11 (3)to fill up the free area, resulting in a layout shown in FIG. 11 (4).Finally, the segment numbers are revised into consecutive numbersarranged in an ascending order in the time axis direction to result in alayout shown in FIG. 11 (5). As shown in FIG. 11 (5), the resultingcontinuous blocks of the signal at their physical locations on the disceach have a length greater than the equivalent of the 1-minuterecording/playback time length with the playback order remainingunchanged. Thus, the number of seek operations is reduced, allowing aplayback operation to be carried out smoothly. In this way, a file of asignal on the disc can be optimized with ease.

6 Editing Details

Next, the editing technique shown in FIG. 9 is explained in detail. FIG.12 is a diagram showing a signal to be edited in the embodiment. Asshown in the figure, segments A, C1, C2 and C3 constitute a continuoussequence of data. Assume that segment B is inserted between segments Aand C1. Let symbols a, c1, b, c2 and c3 denote the lengths of segment A,C1, B, C2 and C3 respectively. Editing technique applied to a variety ofcases are explained as follows.

A Lengths a and B Equal to or Larger than the 1-MinuteRecording/Playback Time Length

FIG. 13 (1) is a diagram showing a case in which segment B to beinserted completes the data at segment C1. Since segments C2 and C3 ofthe signal shown in FIG. 12 do not exist, segment B is merely insertedbetween segments A and C1. However, it is not necessary to physicallymove segments B and C1. What needs to be done is just changing theplayback pointers to A-->B-->C1. In this case, since segment C1 is thesegment to be played back last,

-   -   there is no triggered seek operation after segment C1. Thus, the        length c1 of segment C1 can be smaller than 1 minute of playback        time.

FIG. 13 (2) is a diagram showing a case in which the data continues tosegment C3. Even in this case, segment B is just inserted betweensegments A and C1 provided that the length c1 of segment C1 is at leastan equivalent of the 1-minute recording/playback time length. That is tosay, by merely changing the playback pointers from A-->C1-->C2-->C3 toA-->B-->C1-->C2-->C3, insertion on the time axis is completed withoutthe need to physically inserts segments A and C1. In this case, thelength c2 of segment C2 must be of course at least an equivalent of the1-minute recording playback time length as is the case with the lengthc1 of segment C1. To be played back last, however, the length c3 ofsegment C3 can be smaller than the 1-minute recording/playback timelength.

Much like FIG. 13 (2), FIG. 13 (3) is a diagram showing a case in whichthe data continues to segment C3. In the latter case, however, thelength c1 of segment C1 is smaller than the 1-minute recording/playbacktime length. Therefore, if segment B is merely inserted between segmentsA and C1, the amount of data temporarily stored in the read buffermemory during the operation to playback segment C1 having a length c1smaller than the 1-minute recording/playback time length will not belarge enough to be used as an output playback signal during a seekoperation accompanying a track jump from segment C1 to segment C2following the operation to playback segment C1 in the playbackoperation. In order to solve this problem caused by the small length c1of segment C1, the data is edited by adopting a technique shown in FIG.13 (4), a diagram showing an editing technique which comprises the stepsof:

-   -   allocating a free area having a size of at least an equivalent        of the 1-minute recording/playback time length;    -   concatenating segment C1 with a portion at the head of segment        C2 denoted by notation “C2-(1)” in the figure to form a lump of        data having a size equal to that of the allocated free area; and    -   physically relocating the lump of data to the allocated free        area to fill up the area.

It should be noted that, if a free area having a size of at least anequivalent of the 1-minute recording/playback time length can not beallocated, the editing can not be done and is thus ended unsuccessfully.

By physically relocating the lump of data in the editing techniquedescribed above, a seek operation following an operation to play back acontinuous segment having a size smaller than the 1-minuterecording/playback time length can be eliminated provided that theremaining part of segment C2 denoted by notation “C2-(2)” in the figureafter removing the portion at the head of segment C2 de noted bynotation “C2-(1)” is at least an equivalent of the 1-minuterecording/playback time length in size. In this case, the editing workis completed successfully.

If the remaining part of segment C2 denoted by notation “C2-(2)” issmaller an equivalent of the 1-minute recording/playback time length insize, however, the amount of data stored temporarily stored in the readbuffer memory to be output as a playback signal during a seek operationaccompanying a track jump from the remaining part of segment C2 denotedby notation “C2-(2)” to segment C3 will be smaller than the 1-minuterecording/playback time length. In order to solve this problem caused bythe small length of the remaining part denoted by notation “C2-(2)” ofsegment C2, the data is edited by adopting a technique shown in FIG. 13(5), a diagram showing an editing technique which comprises the stepsof:

-   -   allocating a free area having a size of at least an equivalent        of the 1-minute recording/playback time length behind the        relocated portion at the head of segment C2 denoted by notation        “C2-(1)”;    -   concatenating the remaining part of segment C2 denoted by        notation “C2-(2)” with a portion at the head of segment C3        denoted by notation “C3-(1)” in the figure to form a lump of        data having a size equal to that of the allocated free area; and    -   physically relocating the lump of data to the allocated free        area to fill up the area.

By physically relocating the lump of data in the editing techniquedescribed above, a seek operation following an operation to play back acontinuous segment having a size smaller than the 1-minuterecording/playback time length can be eliminated. It should be notedthat, if a free area having a size of at least an equivalent of the1-minute recording/playback time length can not be allocated behind therelocated portion at the head of segment C2 denoted by notation“C2-(1)”, the area originally occupied by segment C2 with a guaranteedsize equal to or larger than the 1-minute recording/playback time lengthcan be used as a free area.

The editing technique shown in FIG. 13 (5) can be applied to subsequentsegments C4 and C5 if they exist after segment C3.

B Length a of Smaller than the 1-Minute Recording/Playback Time Lengthand Length b Equal to or Larger than the 1-Minute Recording/PlaybackTime Length

In this case, if segment B is merely inserted between segments A and C1,the amount of data temporarily stored in the read buffer memory duringan operation to playback segment A having a length smaller than the1-minute recording/playback time length will not be large enough to beused as an output playback signal during a seek operation accompanying atrack jump from segment A to segment B following the operation toplayback segment A in the playback operation. In order to solve thisproblem caused by the small length a of segment A, the data is edited byadopting a technique shown in FIG. 14 (2), a diagram showing an editingtechnique which comprises the steps of:

-   -   allocating a free size of at least an equivalent of the 1-minute        recording/playback time length;    -   concatenating segment A with a portion at the head of segment B        denoted by notation “B-(1)” in the figure to form a lump of data        having a size equal to that of the allocated free area; and    -   physically relocating the lump of data to the allocated free        area to fill up the area.

It should be noted that, if a free area having a size of at least anequivalent of the 1-minute recording/playback time length can not beallocated, the editing can not be done and is thus ended unsuccessfully.

By physically relocating the lump of data in the editing techniquedescribed above, a seek operation following an operation to play back acontinuous segment having a size smaller than the 1-minuterecording/playback time length can be eliminated provided that theremaining part of segment B denoted by notation “B-(2)” in the figureafter removing the portion at the head of segment B denoted by notation“B-(1)”, that is a length {b−(1−a)}, is at least an equivalent of the1-minute recording/playback time length in size. In this case, theediting work is completed successfully. It is thus necessary to form ajudgment as to whether or not the length {b−(1−a)} is at least anequivalent of the 1-minute recording/playback time length or a length(a+b) is at least an equivalent of the 2-minute recording/playback timelength.

If (a+b) is at least an equivalent of the 2-minute recording/playbacktime length in size, the amount of data temporarily stored in the readbuffer memory during an operation to playback the remaining part ofsegment B denoted by notation “B-(2)” will be large enough to be used asan output playback signal during a seek operation accompanying a trackjump from the remaining part of segment B to segment C1 following theoperation to playback the remaining part of segment B in the playbackoperation. Then, it is necessary to form a judgment as to whether or,not the length c1 of segment C1 is at least an equivalent of the1-minute recording/playback time length, or whether or not segment C1 isthe last segment of the data. If either of the conditions is satisfied,a seek operation following an operation to play back a continuoussegment having a size smaller than the 1-minute recording/playback timelength can be eliminated in which case, the editing work is completedsuccessfully. If both the conditions are not satisfied, on the otherhand, the problem caused by the small length c1 segment C1 can be solvedby applying a method similar to the editing technique shown in FIGS. 13(3) to (5) of Subsection A with the title “Lengths a and b equal to orlarger than the 1-minute recording/playback time length” describedabove.

To put it in detail, if (a+b) is smaller than the 2-minuterecording/playback time length in size, the problem caused by the smalllength of the remaining part denoted by notation “B-(2)” of segment B issolved by applying an editing technique shown in FIG. 14 (3), a diagramshowing an editing technique of forming a judgment as to whether a freearea having a size equal to or larger than the 1-minuterecording/playback time length can be allocated. If such an area can beallocated, the formation of the judgment is followed by the steps of:

-   -   allocating the free area;    -   concatenating the remaining part of segment B denoted by        notation “B-(2)” with a portion at the head of segment C1        denoted by notation “C1-(1)” in the figure to form a lump of        data having a size equal to that of the allocated free area; and    -   physically relocating the lump of data to the allocated free        area to fill up the area.

If such a free area can not be allocated, on the other hand, the lumparea is relocated to the area used to be occupied by segment B. Ineither case, segment B and segment C are fragmented.

After the lump of data has been relocated, it is necessary to form ajudgment as to whether or not the length (a+b+c1−2) of the remainingpart denoted by notation “C1-(2)” of segment C1 after removing theportion denoted by notation “C1-(1)” is at least an equivalent of the1-minute recording/playback time length, or whether or not the remainingpart denoted by notation “C1-(2)” of segment C1 is the last portion ofthe data. If either of the conditions is satisfied, a seek operationfollowing an operation to play back a continuous segment having a sizesmaller than the 1-minute recording/playback time length can beeliminated in which case, the editing work is completed successfully. Ifboth the conditions are not satisfied, on the other hand, the problemcaused by the small length of the remaining part denoted by notation“C1-(2)” of segment C1 can be solved by applying an editing techniqueshown in FIG. 14 (4), a diagram showing an editing technique whichcomprises the steps of:

-   -   allocating a free area having a size of at least an equivalent        of the 1-minute recording/playback time length;    -   concatenating the remaining part of segment C1 denoted by        notation “C1-(2)” with a portion at the head of segment C2        denoted by notation “C2-(1)” in the figure to form a lump of        data having a size equal to that of the allocated free area; and    -   physically relocating the lump of data to the allocated free        area to fill up the area.

After the lump of data has been relocated, it is necessary to form ajudgment as to whether or not the length of the remaining part denotedby notation “C2-(2)” of segment C2 after removing the portion denoted bynotation “C2-(1)” is at least an equivalent of the 1-minuterecording/playback time length, or whether or not the remaining partdenoted by notation “C2-(2)” of segment C1 is the last portion of thedata. If either of the conditions is satisfied, a seek operationfollowing an operation to play back a continuous segment having a sizesmaller than the 1-minute recording/playback time length can beeliminated in which case, the editing work is completed successfully. Ifboth the conditions are not satisfied, on the other hand, the problemcaused by the small length of the remaining part denoted by notation“C2-(2)” of segment C2 can be solved by applying an editing techniqueshown in FIG. 14 (5), a diagram showing an editing technique whichcomprises the steps of:

-   -   allocating a free area having a size of at least an equivalent        of the 1-minute recording/playback time length;    -   concatenating the remaining part of segment C2 denoted by        notation “C2-(2)” with a portion at the head of segment C3        denoted by notation “C3-(1)” in the figure to form a lump of        data having a size equal to that of the allocated free area; and    -   physically relocating the lump of data to the allocated free        area to fill up the area.        C Length a Equal to or Larger than the 1-Minute        Recording/Playback Time Length and Length b Smaller than the        1-Minute Recording/Playback Time Length

In order to solve this problem caused by the small length b of segmentB, the data is edited by adopting a technique shown in FIG. 15 (2), adiagram showing an editing technique which comprises the steps of:

-   -   allocating a free area having a size of (1−b) right behind        segment B; and    -   relocating a portion at the head of segment C1 denoted by        notation “C1-(1)” in the figure to fill up the free area.

As an alternative, the technique may comprise the steps of:

-   -   allocating a free area having a size of at least an equivalent        of the 1-minute recording/playback time length;    -   concatenating the segment B with the portion at the head of        segment C1 denoted by notation “C1-(1)” in the figure to form a        lump of data having a size equal to that of the allocated free        area; and    -   physically relocating the lump of data to the allocated free        area to fill up the area.

It should be noted that, if a free area having a size of at least anequivalent of the 1-minute recording/playback time length can not beallocated in either case, the editing can not be done and is thus endedunsuccessfully.

After the lump of data has been relocated, it is necessary to form ajudgment as to whether or not the length of the remaining part denotedby notation “C1-(2)” of segment C1 after removing the portion denoted bynotation “C1-(1)” is at least an equivalent of the 1-minuterecording/playback time length, or whether or not the remaining partdenoted by notation “C1-(2)” of segment C1 is the last portion of thedata, that is, whether or not segment C1 is the last segment of thedata. If either of the conditions is satisfied, a seek operationfollowing an operation to play back a continuous segment having a sizesmaller than the 1-minute recording/playback time length can beeliminated in which case, the editing work is completed successfully. Ifboth the conditions are not satisfied, on the other hand, the problemcaused by the small length of the remaining part denoted by notation“C1-(2)” of segment C1 can be solved by applying editing techniquesshown in FIGS. 15 (3) and 15 (4) which are similar to those shown inFIGS. 13 (4) and 13 (5) described earlier respectively.

D Both Lengths a and b Smaller Than the 1-Minute Recording/Playback TimeLength

In this case, editing work for a total length (a+b) equal to or largerthan the 1-minute recording/playback time length is different from thatfor a total length (a+b) smaller than the 1-minute recording/playbacktime length. The following description begins with a case shown in FIG.16 (1) in which the total length (a+b) is smaller than the 1-minuterecording/playback time length. The case requires a technique shown inFIG. 16 (2), a diagram showing an editing technique which comprises:

-   -   allocating a free area having a size of at least an equivalent        of the 1-minute recording/playback time length;    -   concatenating segments A and B with a portion at the head of        segment C1 denoted by notation “C1-(1)” in the figure to form a        lump of data having a size equal to that of the allocated free        area; and    -   physically relocating the lump of data to the allocated free        area to fill up the area.

As an alternative, the editing technique may comprise the steps of:

-   -   allocating a free area having a size of (1−b) right behind        segment B; and    -   physically relocating a portion at the head of segment C1        denoted by notation “C1-(1)” in the figure to fill up the free        area.

It should be noted that, if a free area having a size of at least anequivalent of the 1-minute recording/playback time length can not beallocated in either case, the editing can not be done and is thus endedunsuccessfully.

After the lump of data has been relocated, it is necessary to form ajudgment as to whether or not the length of the remaining part denotedby notation “C1-(2)” of segment C1 after removing the portion denoted bynotation “C1-(1)” is at least an equivalent of the 1-minuterecording/playback time length, or whether or not the remaining partdenoted by notation “C1-(2)” of segment C1 is the last portion of thedata, that is, whether or not segment C1 is the last segment of thedata. If either of the conditions is satisfied, a seek operationfollowing an operation to play back a continuous segment having a sizesmaller than the 1-minute recording/playback time length can beeliminated in which case, the editing work is completed successfully. Ifboth the conditions are not satisfied, on the other hand, the problemcaused by the short length of the remaining part denoted by notation“C1-(2)” of segment C1 can be solved by applying an editing techniquesshown in FIGS. 16 (3) and 16 (4) which are similar to those shown inFIGS. 13 (4) and 13 (5) described earlier respectively.

The following is description of a case shown in FIG. 17 (1) in which thetotal length (a+b) is at least an equivalent of the 1-minuterecording/playback time length. In this case, it is necessary to apply atechnique shown in FIG. 17 (2), a diagram showing an editing techniquewhich comprises:

-   -   allocating a free area having a size of at least an equivalent        of the 1-minute recording/playback time length;    -   concatenating segment A with a portion at the head of segment B        denoted by notation “B-(1)” in the figure to form a lump of data        having a size equal to that of the allocated free area; and    -   physically relocating the lump of data to the allocated free        area to fill up the area.

It should be noted that, if a free area having a size of at least anequivalent of the 1-minute recording/playback time length can not beallocated in either case, the editing can not be done and is thus endedunsuccessfully.

After the lump of data has been relocated, it is necessary to form ajudgment as to whether or not the length of the remaining part denotedby notation “C1-(2)” of segment C1 after removing the portion denoted bynotation “C1-(1)” is at least an equivalent of the 1-minuterecording/playback time length, or whether or not the remaining partdenoted by notation “C1-(2)” of segment C1 is the last portion of thedata, that is, whether or not segment C1 is the last segment of thedata. If either of the conditions is satisfied, a seek operationfollowing an operation to play back a continuous segment having a sizesmaller than the 1-minute recording/playback time length can beeliminated in which case, the editing work is completed successfully. Ifboth the conditions are not satisfied, on the other hand, the problemcaused by the short length of the remaining part denoted by notation“C1-(2)” of segment C1 can be solved by applying an editing techniquesshown in FIGS. 17 (4) and 17 (5) which are similar to those shown inFIGS. 13 (4) and 13 (5) described earlier respectively.

In the cases discussed in subsections A to D, segment B to be insertedis recorded in one continuous area. The following subsections describecases in which segment B comprises sub-segments B1, B2 and B3 which arerecorded in areas physically separated from each other. It is assumedthat, as a single segment, there is an assurance that data of segment Bcan be reproduced without generating a playback time break caused by aseek operation which is in turn attributed to a track jump. That is tosay, sub-segments B1 and B2 each have a length equal to or larger thanthe 1-minute recording/playback time length. To be played back last, onthe other hand, sub-segment B3 can be at least or smaller than the1-minute recording/playback time length in size.

E Both Lengths a and b (=b1+b2+b3) Equal to or Larger than the 1-MinuteRecording/Playback Time Length

Processing for a case in which sub-segment B3 has a length b3 equal toor larger than the 1-minute recording/playback time length is differentfrom a case with the length b3 smaller than the 1-minuterecording/playback time length. In the former case shown in FIG. 18 (1),it is necessary to form a judgment as to whether or not the length c1 ofsegment C1 is at least an equivalent of the 1-minute recording/playbacktime length or whether or not segment C1 is the last segment of thedata. If either of the conditions is satisfied, a seek operationfollowing an operation to play back a continuous segment having a sizesmaller than the 1-minute recording/playback time length can beeliminated in which case, the editing work is completed successfully bymerely correcting the playback pointers. If both the conditions are notsatisfied, on the other hand, the problem caused by the short length ofsegment C1 can be solved by applying an editing techniques shown inFIGS. 18 (2) and 18 (3) which are similar to those shown in FIGS. 13 (4)and 13 (5) described earlier respectively.

FIG. 19 (1) is a diagram showing a case in which the length b3 ofsub-segment B3 is smaller than the 1-minute recording/playback timelength. In this case, it is necessary to apply a technique shown in FIG.19 (2), a diagram showing an editing technique which comprises:

-   -   allocating a free area having a size of at least an equivalent        of the 1-minute recording/playback time length;    -   concatenating sub-segment B3 with a portion at the head of        segment C1 denoted by notation “C1-(1)” in the figure to form a        lump of data having a size equal to that of the allocated free        area; and    -   physically relocating the lump of data to the allocated free        area to fill up the area.

After the lump of data has been relocated, it is necessary to form ajudgment as to whether or not the length of the remaining part denotedby notation “C1-(2)”of segment C1 after removing the portion denoted bynotation “C1-(1)” is at least an equivalent of the 1-minuterecording/playback time length, or whether or not the remaining partdenoted by notation “C1-(2)” of segment C1 is the last portion of thedata, that is, whether or not segment C1 is the last segment of thedata. If either of the conditions is satisfied, a seek operationfollowing an operation to play back a continuous segment having a sizesmaller than the 1-minute recording/playback time length can beeliminated in which case, the editing work is completed successfully. Ifboth the conditions are not satisfied, on the other hand, the problemcaused by the short length of the remaining part denoted by notation.“C1-(2)” of segment C1 can be solved by applying an editing techniquesshown in FIGS. 19 (3) and 19 (4) which are similar to those shown inFIGS. 13 (4) and 13 (5) described earlier respectively.

F Length a of Smaller than the 1-Minute Recording/Playback Time Lengthand Length b (=b1+b2+b3) Equal to or Larger than the 1-MinuteRecording/Playback Time Length

FIG. 20 (1) is a diagram showing a case in which the length a is smallerthan the 1-minute recording/playback time length and the length b(=b1+b2+b3) is at least an equivalent of the 1-minute recording/playbacktime length. In this case, it is necessary to apply a technique shown inFIG. 20 (2), a diagram showing an editing technique which comprises:

-   -   allocating a free area having a size of at least an equivalent        of the 1-minute recording/playback time length;    -   concatenating segment A with a portion at the head of        sub-segment B1 denoted by notation “B1-(1)” in the figure to        form a lump of data having a size equal to that of the allocated        free area; and    -   physically relocating the lump of data to the allocated free        area to fill up the area.

After the lump of data has been relocated, it is necessary to form ajudgment as to whether or not the length of the remaining part denotedby notation “B1-(2)” of sub-segment B1 after removing the portiondenoted by notation “B1-(1)” is at least an equivalent of the 1-minuterecording/playback time length. If the remaining part denoted bynotation “B1-(2)” of sub-segment B1 is at least an equivalent of the1-minute recording/playback time length in length, a seek operationfollowing an operation to play back a continuous segment having a sizesmaller than the 1-minute recording/playback time length can beeliminated in which case, the editing work is completed successfully. Ifthe remaining part denoted by notation “B1-(2)” of sub-segment B1 issmaller than the 1-minute recording/playback time length in length, onthe other hand, it is necessary to apply a technique shown in FIG. 20(3), a diagram showing an editing technique which comprises:

-   -   allocating a free area having a size equal to or larger than the        1-minute recording/playback time length;    -   concatenating the remaining part denoted by notation “B1-(2)” of        sub-segment B1 with a portion at the head of sub-segment B2        denoted by notation “B2-(1)” in the figure to form a lump of        data having a size equal to that of the allocated free area; and    -   physically relocating the lump of data to the allocated free        area to fill up the area.

After the lump of data has been relocated, it is necessary to form ajudgment as to whether or not the length of the remaining part denotedby notation “B2-(2)” of sub-segment B2 after removing the portiondenoted by notation “B2-(1)” is at least an equivalent of the 1-minuterecording/playback time length. If the remaining part denoted bynotation “B2-(2)” of sub-segment B2 is at least an equivalent of the1-minute recording/playback time length in length, a seek operationfollowing an operation to play back a continuous segment having a sizesmaller than the 1-minute recording/playback time length can beeliminated in which case, the editing work is completed successfully. Ifthe remaining part denoted by notation “B2-(2)” of sub-segment B1 issmaller than the 1-minute recording/playback time length in length, onthe other hand, it is necessary to repeat the processing described abovefor the remaining part denoted by notation “B2-(2)” of sub-segment B2and sub-segment B3.

In the editing techniques described above, the minimum size of acontinuous segment is set at a value equivalent to the 1-minuterecording/playback time length. It should be noted that this value canbe changed depending on the seek time, the rotation wait time and thesettle time of the signal playback apparatus. For example, the minimumsize of a continuous segment is set at a multiple or a fraction of theequivalent of the 1-minute recording/playback time length. In addition,the minimum size of a continuous segment can be set in dependence onfactors other than the time related parameters. To be more specific, theminimum size of a continuous segment can be set at an equivalence of apredetermined amount of data, the GOP unit used in the MPEG encodingprocess or a data unit used in internal processing such a packet or ablock.

As described in detail above, according to the present invention, theamount of data stored in advance in the read buffer memory during thetime is large enough to eliminate a next playback time break, that is,to be output during a next track jump in a seek operation entailing notonly a seek time, but also a rotation wait time and a settle time. As aresult, the eventual playback signal can be generated continuously. Inaddition, the time it takes to optimize data recorded in the disc bydefragmentazion of the data can be reduced substantially.

1-7. (canceled)
 8. A data recording method for recording data onto arecording medium to be reproduced by a reproduction device having abuffer memory for temporarily storing the data, comprising the steps of:inserting variable bit-rate data having a size smaller than apredetermined length; wherein the variable bit-rate data is encoded inMPEG format, and said predetermined length being determined on the basisof the length of time for which the variable bit-rate data can bereproduced at a maximum bit-rate without an interruption; combining theinserted data with recorded data adjacent to the inserted data to form adata unit of at least said predetermined size; recording the data unitin a continuous recordable area on the recording medium, in which therecording step includes detecting the length of a remaining portion ofthe next part of the data, that was not recorded, and if said remainingportion has a length less than said predetermined length, then locatinganother non-recorded area on said recording medium having a size of atleast said predetermined length.